html, body{
    height: 100%;
    margin: 0;
}
h1, footer{
    margin: 0;
}
nav{
    position: fixed;
    width: 100%;
    text-align: center;
    padding: 1% 0;
}
nav>a{
    padding: 0 2%;
    padding: 16px 32px;
    font-size: 1.5em;
    font-family: Impact, Haettenschweiler, 'Arial Narrow Bold', sans-serif;
    text-align: center;
    text-decoration: none;
    color: white;
    /* inline-block will bring different effect of location */
    display: inline-block;
    -webkit-transition-duration: 0.4s;
    transition-duration: 0.4s;
    cursor: pointer;
}
nav>a:hover {
    color: black;
    background-color:white;
}
.main{
    min-height: 100%;
    text-align: center;
    width: 100%;
    height: 100%;
    font-size: 2em;
    color: black;
    background-color: darkcyan;
}
footer{
    margin-top: -10px;
    bottom: auto;
    text-align: center;
    font-size: 2em;
    color: beige;
    background-color: gray;
}
